Adhesive-coated sheet material



PaientedFeb. 25, 1941 I UNITED STATES PATENT OFFIC Benjamin AsnesandErnest L. Kallander, Framingham, Mass, assignon to DennisonManufacturing Company, Frnminghnm, Hill, a corporation of MassachusettsNo Drawing. Application January '24, 1939,

, Serial No. 25:,880

' Claims. (61. zen-15w This invention relates to adhesive-coated sheet.and non-aqueous emulsions of wax and rubber or material of the typeadapted to be activated torubber-like materials may be compounded withadhesiveness either by the application of heat or vinyl resins toproduce a composition which satisby the application of a suitablesolvent. It apfies the aforementioned objectivesand that when 5 plies tosuch articles of commerce as labels, seala vinyl resin is compoundedwith wax-rubber 5 ing tape, papers for packaging purposes, and pa.-mixture' it not only imparts strength, firmness, pers designed to vbeapplied to various suriacestor true elasticity and resistance todeformation, but purposes of protection v and identification. Here-,also increases the thermo-plasticity of the comtofore such compositionsas have been available Po o Without detracting from s. adhsivehess havesufiered from the disadvantages of being and quick tack. We have alsoobserved that cer- 10 either too slow in adhesive activation orrequirtain of the desirable characteristics of the rubing too'hightemperature or have been unduly af.- 1- e-, its inherent plia y dadhesiveness, fected by the temperature of warm climates in as well asthose of the wax, i. e., the wetting and torag resulting in blocking orsticking together super-cooling characteristics, are not materially ofadjacent sheets in a bundle. altered or impaired by the vinyl resin, andthat Adhesive coated sheet material of the aforethe inherent tackinessof the rubber at normal said type made in accordance with priorractemperatures and the fluidity of the waxy and the tices havesometimes been made of paraffin-rub consequent 10W film Strength televated p ber mixtures. We propose to discuss such mixtures aresufliciently altered by the vinyl resin .to

t r s since they are more closely related to apovercome the diiilcultiesattributable to these 0 plicants invention and will therefore serve as acharacteristics in Compositions o e o esa point of reference. If thecomposition is for use yp in cases where a wide range of adhesion andre- The relative proportions o r r n sistance t-o blocking are ofprimary importance, Vinyl resin m be Varied throughout a Wide it is theusual practice to increase thepropoption range, but as a general rulemore satisfactory re- 25 of paraffin to an extent sufllcient to obtainthese fl ts y be O t e i t e y r r co te t characteristics, even thoughin so doing the adis of the order of 10 to 40% of the wax, and thehesive strength is materially impaired; on the vinyl resin content isbetween 4 and 15% of the other hand where strong adhesion is the imo bede stood that these figportant consideration the proportion of rubbermay be varied in accordance with the ph 30 is increased so as to producethe desired result, ri tics of the particular type of rubnotwithstandingthat the resulting composition Wax and yl re ins lected for use. In mayhave a relatively low range of adhesion and v the r l in mpo ition,after appoor blocking quality. For us int r-medi t plicationto thesurface of a sheet material and these extreme th proportion 1 paramn delimination of the solvent or water as the case 35 rubber are varied toefiect a compromise reasony be. consists essentially of the dispersionably satisfactory for the general requirements of wherein 15118 Waxconstitutes t e i lls p e 1 the trade. and the rubber and vinyl resinthe dispersed The principal objects of the present invention Phase Theresulting a ing is characterized by 40 are to overcome the aforesaiddisadvantages and a rel ively lower softening point y t r ntion 4 toprovide an improved adhesive of the aforesaid of viscosity d fi stren hat elevated temtype which, when a lied t h t t ri properatures thanwould be possible of attainment duces a uniform colorless coating havinggood in compositions consisting essentially of D ra inblockingcharacteristics and, when activated .to rubber e q v ent mix ures, andat normal adhesiveness either by the applications! heat or temperaturesthe Strength and character of the 45 by the application of a suitablesolvent, possesses 1 18 Such as effectively o i t lo in Furquick tack, awide range or adhesion and a b t,- thermore, when a composition preparedin acter all-r und balanc 1 mmi F th cordance with .the presentinvention is dispersed jects relate to various advantageouscharacterlsin 8 given solvent. e viscosity o the dispersion tics or ourimproved composition which will be is substantially low r th t at of a oposition 50 apparent from a consideration of the following ;p P inaccordance i the Prior r Dract tm wherein we have disclosed flfierenttice and having substantially the same total solids, examples ofcompositions prepared inaccordance content. Moreover, as compared withprior art with the present invention. compositions possessing the sameor similar de- We have discovered that aqueous dispersions gree ofadhesion. We fin t our composition 55 contains substantially less rubberand hence has better aging qualities and greater resistance to blocking.

A further advantage of our composition is that it may be quicklycompounded in any of the conventional types of mixing apparatus, andwhen compounded it may be readily applied at comparatively lowtemperatures without necessitating the use of expensive equipment.

The term rubber as used in the formulae described herein is intended tomean the crepe rubber and smoked sheets of commerce, derived from thelatex and Hevea Braziliensis and also to include generally both naturaland synthetic rubber or their equivalents, and also such naturallyoccurring materials as balata, guttapercha, gutta-siak, gutta-kayak,gums such as pontianiak and guayule, and certain wild rubbers andrubber-like resins (in which case a. larger quantity must be used informulation than if crepe rubber, or smoked sheets is used, depending onthe characteristics of the substitute rubber) the term wax" is intendedto include not only such materials as beeswax, paraflin, ceresin,spermacetl, carnauba and candelilla, but also their natural andsynthetic equivalents, and mixtures thereof; and the term vinyl resin"is intended to include such polymerized products as are derived fromcompounds having the general formula CHa=CR1Rz, wherein R1 is hydrogenor a hydrocarbon residue, and R2 is anhydroxyl, carboxyl, cyanogen,halogen, alkoxy, acetyl, halogenated acetyl residue, etc., and includespolycrylic-acid, and polymethacrylic acid, or the esters, amides,nitrides, chlorides, or anhydrides of these acids, polyvinyl halides andacetate.

The particular compounding procedure will of course vary depending uponwhether a nonaqueous or an aqueous dispersion is to be prepared. Inpreparing non-aqueous dispersions the three essential ingredients may beseparately dissolved or dispersed in suitable solvents such as naphthaand/or benzol, and subsequently thoroughly mixed, after which theconcentration of the resulting product may, if desired, be adjusted toproduce the preferred total solids content for the most satisfactoryapplication.

Specific examples illustrating the preparation of non-aqueousdispersions are as follows:

El'cample 1 20 pounds of paraiiin wax, preferably having a melting pointof about 140 F., are melted in a jacketed container and 2 pounds ofrosin are added. The temperature required for melting the paraflln androsin is about 150 F., and when these ingredients have been melted 40pounds of naphtha and 20 pounds benzol may then be,

added, whereupon the temperature is lowered to approximately 105 F. andthe solution is completed 'at this temperature. 5 pounds of pale creperubber are then added and the mixture thoroughly agitated to effectcomplete dissolution of the ingredients. In' a separate container asecond solution is prepared, consisting of 2 pounds of polymerized vinylresin and 3 pounds the like. the application preferably being carriedout at a temperature of,the order of 105 F.

Although the above specified proportions are preferred, we find that thewax content may be varied between 15 and 40 pounds, that the rosincontent may run as high as 30% of the wax, that the rubber content mayvary from 10 to 40% of the wax, and that the vinyl resin content mayvary from 10 to 30% of the wax.

A composition prepared in the manner above described has a relativelyhigh viscosity so that undue penetration of the stock is notencountered, and yet adequate adhesion to the sheet material isobtained. Upon being spread upon the sheet material in a relatively thinfilm, the

greater part of the solvent is rapidlyevaporated when it passes into aheated zone, and hence the resulting film quickly forms or sets to asolid or gelled condition. The film when cooled to normal temperature isfree from tackiness and has no tendency to block.

Example 2 Separate solutions or dispersions of the ingredients areprepared as follows:

(a) 5 parts of wax or the like ester of a higher fatty acid are blendedwith 6 parts of paraffin, preferably having a melting point of about 104F., and the mixture dissolved in about 15 parts of benzol. 1

('b) 10 parts of balata and 1 part of crepe rubber, are dissolved inapproximately 20 parts of benzol.

(c) 1 part of chlorinated regenerated or cyclizedrubber is dissolved in5 parts of benzol.

(d) 2 parts vinyl resin (preferably Vinylite A) are dissolved in 3 partsof benzol.

After having prepared the above solutions (b) and (c) are added tosolution (a) with 30 parts of naphtha, after which (d) and 5 parts ofalcohol are preferably added, the compounding Ingredients Range Wax22-130 Balata 30-75 Cr p rubber 3-8 Vin resin 6-15 Chlorinated rubber -2The amount of solvent may be varied to produce a total solids contentfrom about 25% to 75%, depending upon the conditions under which thefinished product is to be applied, and although benzol and naphthaconstitute the preferred solvents, we have found that the addition ofabout alcohol is beneficial. After having-prepared the solution as abovedescribed, it may be drawn off, strained and transferred to a coatingmachine for application to various types of sheet material, includingpaper, Cellophane,- cloth, metal foil and the like.

In preparing aqueous dispersions or emulsions it is necessary first toemulsify the wax and resins and to employ rubber latex or the -likedispersions in place of dry rubber. An illustrative procedure is asfollows:

Example 3 20 parts of paraffin, preferably having a melting point ofabout 140 F., are blended with 2 parts of rosin (grade H) and 22 partsof this mixture are emulsified with 100 parts of water and 6 parts ofammonium stearate soap, preferably prepared by-reacting about 64 partsstearic acid with 20 parts concentrated ammonia. The resulting productis an aqueous wax-rosin emulsion in which the ammonium stearate soapacts not be expected to flow from a single component, 4

namely (1) less heating required to soften the gumming for applicationand (2) greater rigidity and strength at room temperatures.

A self-supporting sheet material may be made from the compoundsdescribed above by spreading I on a surface to which the compound willnot adhere, as for instance a highly polished metal drum, drying out thesolvent and stripping the fiber and rolling up. I 1

It should be understood. that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

We claim: a

1. Sheet material having a thermoplastic coating comprising 15 to partsof wax, from 2 to 12 parts vinyl resin, and from 2 to 16 parts rubber.

2. Sheet materialhaving a thermoplastic coating comprising approximately20 parts paraflin, 2 parts rosin, 5 parts rubber and 2 parts vinylresin.

ing comprising from 22 to 130 parts wax, from 30 to 80 partsrubber, from6 to 15 parts vinyl resin, and not more than 2'parts chlorinated rubber.

3. Sheet material having a thermoplastic coat 4. Sheet material having athermoplastic coat- 20 ing comprising approximately 60 parts rubber,parts wax, 11 parts vinyl'resin and 0.5 part of chlorinated rubber.

5. Sheet material having a thermoplastic coating comprising 20 partsparailin wax,' '2 parts resin, 5 parts rubber and'2partsvinyl resin.

ERNEST L. KALLANDER. BENJAMIN ASNES.

